U.S. Pat. No. 3,901,574 discloses and claims a cylindrical electrical connector assembly comprising a connector plug and a connector receptacle. The plug part has a rotational coupling ring thereon which has internal threads that mate with external threads on the surface of the receptacle, the arrangement being such that when the parts are mated, the coupling ring is rotated to draw or pull the plug and receptacle together until the contact terminals in the two parts are fully engaged with each other. The connector assembly described in U.S. Pat. No. 3,901,574 is entirely of molded plastic parts and it can therefore be produced at a significantly lower cost than conventional cylindrical electrical connectors which consist of a plastic insert mounted in a metallic shell. Connectors of the type disclosed in the above identified U.S. Pat. No. have many of the advantages of conventional cylindrical electrical assemblies and can therefore be used under circumstances where the cost of a composite cylindrical connector (the type comprising a metallic shell and an insert) cannot be justified.
While connectors of the type shown in U.S. Pat. No. 3,901,574 are presently being widely used, it would be desirable to provide as an option a low-cost metallic shell on the plug part and on the receptacle part of the assembly. A low-cost shell on the connector parts would be desirable where the connector assembly is used under severe conditions and where it will necessarily be subjected to abusive treatment. It would also be desirable to provide a metallic shell on a connector assembly shown in U.S. Pat. No. 3,901,574 for shielding purposes under many conditions.
It is accordingly one of the objects of the present invention to provide a low-cost cylindrical electrical connector having metallic shells in surrounding relationship to the insulating inserts of the connector assembly.
In accordance with a further aspect thereof, the invention is directed to the achievement of improved keying means for cylindrical electrical connectors. It is presently common practice to provide on the mating parts of a connector assembly keys and keyways which permit mating of the two connector parts only when they are in the proper angular orientation for mating; however, it frequently happens that two or more electrical connector assemblies will be used in close proximity to each other and under circumstances where a technician might inadvertently mismate the connector parts of the two connector assemblies. It would be desirable to be able to key the parts uniquely to each other so that such mismating would be impossible. The present invention is directed to the achievement of a keying system which does permit, and provide for, unique keying arrangements for connector assemblies which prevent mismating with connector parts of adjacent connector assemblies.
A preferred embodiment of the invention comprises a connector plug part and a receptacle part, each part comprising a molded insert and a cylindrical shell within which the insert is fitted and retained. The insert of the receptacle part has an integral hood which extends beyond the mating face of the receptacle insert and the shell of the receptacle also has a hood which extends forwardly beyond the insert hood. The plug part comprises an insert and a shell which has an internal surface that is radially spaced from the external surface of the plug insert so that when the two parts are mated, the hood of the receptacle insert will be received between the external surface of the plug insert and the internal surface of the plug shell. The hood of the receptacle shell extends over the external surface of the plug shell when the parts are mated and threads or the like on the external surface of the receptacle shell hood are engaged by threads provided on the internal surface of a coupling ring which is rotationally mounted on the plug shell.
Insert keying means are provided on the external surface of the plug insert and on the internal surface of the hood portion of the receptacle insert defining a first unique keying system, so that these two inserts can be mated only when this keying means is satisfied. Additional keying means are provided on the external surface of the plug shell and on the internal surface of the receptacle shell hood defining a second unique keying system, and this additional keying means must also be aligned before the two connector parts can be coupled to each other. Distinctive or unique keying for a particular connector assembly is achieved when the inserts are assembled to the shells of the two connector parts by mounting the inserts at predetermined locations with a predetermined angular relationship between the insert keying means and the shell keying means. A particular connector assembly having its own distinctive angular relationship between the two keying means cannot therefore be mated with an adjacent connector assembly having a different angular relationship between the two keying means.